In order to study the effect of source and level of the commonly used dietary fats on growth and metabolism of rats fed on low protein diet (rice diet) the weaning white rats were fed on various different experimental diets (see tables 1 and 2) during 11 weeks. The observations were made as follows : 1. Growth: (see table 3 and figures 1-9) In all dietary fats, among the 3 levels, 5% fat level is the best. Especially, the perilla oil group was remarkably good. 10% and 20% fat levels impaired the growth, consequently the growth rates of both 10% and 20% fat level groups were worse than those of Basal group (no fat added). However, 10% and 20% fat levels did not impaired the growth of VII group (10% soy flour added) In 5% fat level, the growth was good in sequence of perilla oil, tallow, sesame oil, soy oil and lard. 2. Feed consumption: (see table 3) In 20% fat level, the feed consumption was lowered. Generally, the feed consumption rate was proportional to the growth rate. In feed efficiency, 5% fat level was the best. 3. Liver weight: (see table 4) In liver weight per 100 G body weight, 20% fat level was the largest. This may be due to the poor body growth and liver fat accumulation. 4. Liver nitrogen: (see table 4) Generally, lower fat level groups showed liver nitrogen. Liver nitrogen is low in the groups of 20% fat level. 5. Liver fat: (see table 4) Generally, higher fat level groups showed higher liver fat. 6. Serum cholesterol: (see table 5) Generally, higher fat level groups showed higher serum cholesterol. Lard, sesame oil, and tallow groups showed higher level and soy oil and perilla oil groups showed lower level. Especially, perilla oil group showed remarkably lower level and VII group (10% soy flour added) showed lower level than VI group (same fat but no soy flour added).